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Fixes BGP IPv6 link local next hop handling.

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When sending 'third party' BGP update, Bird used bogus link local
addresses instead of addresses it received before.
This commit is contained in:
Ondrej Zajicek 2009-04-29 18:58:24 +02:00
parent ad440a570b
commit 4827b69ff4
4 changed files with 54 additions and 23 deletions
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9
proto/bgp/attrs.c
View file

@ -786,13 +786,13 @@ bgp_create_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p
put_u16(z+2, p->local_as);
}
z = bgp_set_attr_wa(ea->attrs+2, pool, BA_NEXT_HOP, sizeof(ip_addr));
z = bgp_set_attr_wa(ea->attrs+2, pool, BA_NEXT_HOP, NEXT_HOP_LENGTH);
if (p->cf->next_hop_self ||
!p->is_internal ||
rta->dest != RTD_ROUTER)
*(ip_addr *)z = p->source_addr;
set_next_hop(z, p->source_addr);
else
*(ip_addr *)z = e->attrs->gw;
set_next_hop(z, e->attrs->gw);
bgp_set_attr(ea->attrs+3, BA_LOCAL_PREF, 0);
@ -862,7 +862,8 @@ bgp_update_attrs(struct bgp_proto *p, rte *e, ea_list **attrs, struct linpool *p
else
{
/* Need to create new one */
bgp_attach_attr_ip(attrs, pool, BA_NEXT_HOP, p->source_addr);
byte *b = bgp_attach_attr_wa(attrs, pool, BA_NEXT_HOP, NEXT_HOP_LENGTH);
set_next_hop(b, p->source_addr);
}
if (rr)

6
proto/bgp/bgp.c
View file

@ -612,13 +612,17 @@ bgp_start_neighbor(struct bgp_proto *p)
#ifdef IPV6
{
struct ifa *a;
p->local_link = ipa_or(ipa_build(0xfe80,0,0,0), ipa_and(p->local_addr, ipa_build(0,0,~0,~0)));
p->local_link = IPA_NONE;
WALK_LIST(a, p->neigh->iface->addrs)
if (a->scope == SCOPE_LINK)
{
p->local_link = a->ip;
break;
}
if (! ipa_nonzero(p->local_link))
log(L_WARN "%s: Missing link local address on interface %s", p->p.name, p->neigh->iface->name);
DBG("BGP: Selected link-level address %I\n", p->local_link);
}
#endif

11
proto/bgp/bgp.h
View file

@ -148,6 +148,17 @@ void bgp_store_error(struct bgp_proto *p, struct bgp_conn *c, u8 class, u32 code
/* attrs.c */
/* Hack: although BA_NEXT_HOP attribute has type EAF_TYPE_IP_ADDRESS, in IPv6
* we store two addesses in it - a global address and a link local address.
*/
#ifdef IPV6
#define NEXT_HOP_LENGTH (2*sizeof(ip_addr))
static inline void set_next_hop(byte *b, ip_addr addr) { ((ip_addr *) b)[0] = addr; ((ip_addr *) b)[1] = IPA_NONE; }
#else
#define NEXT_HOP_LENGTH sizeof(ip_addr)
static inline void set_next_hop(byte *b, ip_addr addr) { ((ip_addr *) b)[0] = addr; }
#endif
void bgp_attach_attr(struct ea_list **to, struct linpool *pool, unsigned attr, uintptr_t val);
byte *bgp_attach_attr_wa(struct ea_list **to, struct linpool *pool, unsigned attr, unsigned len);
struct rta *bgp_decode_attrs(struct bgp_conn *conn, byte *a, unsigned int len, struct linpool *pool, int mandatory);

51
proto/bgp/packets.c
View file

@ -234,10 +234,10 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
{
struct bgp_proto *p = conn->bgp;
struct bgp_bucket *buck;
int size, is_ll;
int size;
int remains = BGP_MAX_PACKET_LENGTH - BGP_HEADER_LENGTH - 4;
byte *w, *tmp, *tstart;
ip_addr ip, ip_ll;
ip_addr *ipp, ip, ip_ll;
ea_list *ea;
eattr *nh;
neighbor *n;
@ -291,26 +291,31 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
*tmp++ = 1;
nh = ea_find(buck->eattrs, EA_CODE(EAP_BGP, BA_NEXT_HOP));
ASSERT(nh);
ip = *(ip_addr *) nh->u.ptr->data;
is_ll = 0;
/* We have two addresses here in 'nh'. Really. */
ipp = (ip_addr *) nh->u.ptr->data;
ip = ipp[0];
ip_ll = IPA_NONE;
if (ipa_equal(ip, p->source_addr))
{
is_ll = 1;
ip_ll = p->local_link;
}
ip_ll = p->local_link;
else
{
/* If we send a route with 'third party' next hop destinated
* in the same interface, we should also send a link local
* next hop address. We use the received one (stored in the
* other part of BA_NEXT_HOP eattr). If we didn't received
* it (for example it is a static route), we do not send link
* local next hop address. It is contrary to RFC 2545, but
* probably the only sane possibility.
*/
n = neigh_find(&p->p, &ip, 0);
if (n && n->iface == p->neigh->iface)
{
/* FIXME: We are assuming the global scope addresses use the lower 64 bits
* as an interface identifier which hasn't necessarily to be true.
*/
is_ll = 1;
ip_ll = ipa_or(ipa_build(0xfe800000,0,0,0), ipa_and(ip, ipa_build(0,0,~0,~0)));
}
ip_ll = ipp[1];
}
if (is_ll)
if (ipa_nonzero(ip_ll))
{
*tmp++ = 32;
ipa_hton(ip);
@ -326,6 +331,7 @@ bgp_create_update(struct bgp_conn *conn, byte *buf)
memcpy(tmp, &ip, 16);
tmp += 16;
}
*tmp++ = 0; /* No SNPA information */
tmp += bgp_encode_prefixes(p, tmp, buck, remains - (8+3+32+1));
ea->attrs[0].u.ptr->length = tmp - tstart;
@ -778,9 +784,18 @@ bgp_do_rx_update(struct bgp_conn *conn,
if (len < 1 || (*x != 16 && *x != 32) || len < *x + 2)
goto bad;
byte *nh = bgp_attach_attr_wa(&a0->eattrs, bgp_linpool, BA_NEXT_HOP, 16);
ip_addr *nh = (ip_addr *) bgp_attach_attr_wa(&a0->eattrs, bgp_linpool, BA_NEXT_HOP, NEXT_HOP_LENGTH);
memcpy(nh, x+1, 16);
ipa_ntoh(*(ip_addr *)nh);
ipa_ntoh(nh[0]);
/* We store received link local address in the other part of BA_NEXT_HOP eattr. */
if (*x == 32)
{
memcpy(nh+1, x+17, 16);
ipa_ntoh(nh[1]);
}
else
nh[1] = IPA_NONE;
/* Also ignore one reserved byte */
len -= *x + 2;